1. The problem statement, all variables and given/known data Assume an elastic collision (ignoring friction and rotational motion). A queue ball initially moving at 3.7 m/s strikes a stationary eight ball of the same size and mass. After the collision, the queue ball's final speed is 2.1 m/s at an angle of theta with respect to its original line of motion. http://img506.imageshack.us/img506/3229/untitledjb3.png [Broken] Find the eight ball's speed after the colli- sion. Answer in units of m=s. 2. Relevant equations p=mv possibly energy equations 3. The attempt at a solution This problem would've been alot easier if the problem provided theta's value. Without theta i only managed to get to this: 3.7=2.1cos(theta)+Vx where Vx is the x component of the 8 ball after collision 0=2.1sin(theta)+Vy where Vy is the y component of the 8 ball after collision should i find theta first? or can I find one of the component's value first and then find theta?